Double-wheel trench cutter is a professional construction equipment of underground diaphragm wall

and its tooth arrangement system is its core component. The parameter design of tooth arrangement system is closely related to rock breaking performance. In this study

a three-dimensional simulation method for milling rock and soil with milling wheel is developed using the continuum-discontinuum element method (CDEM). On this basis

considering the correlation between free surface and milling

the mechanism of the influence of cutting sequence on rock breaking performance of tooth arrangement system is studied

and a numerical generalization model of rock entry sequence is established under the condition of associated milling

in which the number of adjacent free surfaces is preset as the main influencing factor. The results show that: (1) The curves of milling force and milling depth obtained by milling wheel milling rock and soil mass verify the correctness of the numerical simulation method. (2) Compared with the intact rock mass

the peak load of rock samples with single adjacent preset free surface and double adjacent preset free surface decreased by 32.5% and 68.2% respectively

and the energy consumption of rock breaking decreased by 19.8% and 56.6%

respectively. (3) In the tooth arrangement system

the larger the ratio of the double adjacent preset free surfaces to the total number of picks

the lower the overall energy consumption of the tooth arrangement system

and the energy consumption of the heterogeneous tooth arrangement system is lower than that of the sequential one. The research results provide a basis for improving the rock breaking process and tooth arrangement system optimization of double-wheel trench cutter.